Multiwall autoclave



J. s. REID MULTIWALL AUTOCLAVE Filed June 4, 1936 PRESSURE 45-.55

Ram EF 45 vAm/e REDUGING VALVE 1NVENT0R.

" ATTORNEY.

GAS STEAM LIQUID Patented Oct. 4, 10938 l y uN-ireowsr-ArsPATENT ermee MULTIWALL AUTOCLAVE James S. Reid, Cleveland, Ohio, assignor to Ruhatex Products,'lnc., New York, N. Y., a corporation of Delaware t Application June 4, 1936, Serial No. 83,501

2 Claims. (Cl. 23-290) This invention relates to autoclaves usedv in Square inch pressure is reinforced on its opposite gassing and simultaneous heatingv of materials. surface by a back pressure of 6000 pounds per In the manufacture of gas expanded rubber, square inch.` It will be evident that other difthecomponents are mixed to form a dough which ferential Wall pressures than herein disclosed may 5 is inserted in anautoclave; An inert gas at a be used and that the principle of applying conpressure of the order of two hundred atmoscentric pressure chambers results in a relatively pheres or over is forced into the autoclave cham* light Weight, economical and eicient autoclave ber for adsorption by the rubber dough. In the structure. process for manufacturing gas expanded rubber Although gases may be used in the reinforcing 0 asdisclosed in the Denton U. S. Patent #1,905,269 concentric chambers, Iprovide the concentric 10 and in the application Serial No. 717,550 filed chamber pressurey by hydraulic means to avoid Mar. 27, 1934 and assigned to the same assignee any danger of explosion of the autoclave. The

as my present invention, simultaneous heating of explosive action of a wholly gaseous autoclave the rubber dough is effected during the gassing resides in the great expandibility of the gases.

stage. Simultaneous heating is carried on to By employing liquid pressures in the concentric 15 partially vulcanize lthe dough so that upon rechambers, the substantially incompressible liquid moval from the autoclave, the adsorbed inert gas would necessitate no materially greater volume will be retained by the rubber as an individual upon any pressure change when a leak or break cellular structure. occurs.

Higher gaseous pressures than two hundred and The autoclave of my present invention utiliz- 20 fifty atmospheres are desirable for more homoing hydraulic reinforcing pressure chambers geneous and rapid adsorption of thefgas by the would merely collapse or cave-in instead of rubber dough. Moreover, autoclaves constructed explode if a fault vshould occur. in accordance with conventional design for rela- The heating of the autoclave chamber is gentively high pressures, such as live` hundred aterally accomplished by a continuous steam coil 25 mospheres 4and over, for experimental Work, are Wound adjacent the inner chamber of the wall. Very costly as well as dangerous. 'A small leak I have found that unsatisfactory heating results or breakin prior autoclaves may result in an with such an arrangement since the chamber explosion due to the rapid escape of the conned end sections are not sufficiently heated as com-` gases. Y pared to the central section. 30

In accordance with my present invention, I The temperature gradient at the end sections contemplate an autoclavebuilt up of a plurality is greater than the intermediate section of the of concentric chambers having successively dichamber` and I have found that heatingthese minishing pressures applied thereto. The effecend sections to a greater extentthan the intertive pressure upon any one wall of the autoclave mediate section Vresults in uniform and homo- 35 is the difference in the pressures on opposite geneous heating of the rubber dough charge. -sides of the Wall. By maintaining the differen- It is accordingly an object of my present intial `vvall pressure at a relatively low value, for vention to provide a novel autoclave for very high example 2000 pounds per square inch, the maxi-V pressures which is relatively inexpensive and is mum pressure within the autoclave chamber may non-explosive. 40 be readily made a multiple thereof by usingY a Another object of my invention is to provide corresponding number of concentric chambers. a novel autoclave for very high pressures that For. example, ifa chamber pressure of 8000 is relatively light inweight. poundsv is required and the chamber Walls are A further object of my invention is to provide designed for 2000 pounds per square inch diiera novel autoclave having means for uniform 45 ential pressure, the main central chamber and chamberheating.

Athree Aconcentric pressure chambers are required 1 These and other objects of my invention will to successively reduce in` 2000 pound steps the become apparent in the following description internal 8000 pound per square inch pressure to taken in connection with the drawing, in which:

atmosphericpressure outside the autoclave. Figure 1 is a cross-sectional illustration of a 50 The chamber Walls of the autoclave of my prespreferred embodiment of a multi-chamber autoentv invention are designed towithstand the ,difclave. l ferentialpressure, and no wall is required to Figure 2 is a cross-sectional View takenalong wtlistand any extremelyV high pressure...` Thus 2-2 of Figure '1, transverse of the autoclave.

55.` the vinner `wall containing `the .8000 pound' per4 Theautoclave is illustrated vertically in Figure 55 l. However, in many practical installations, a horizontal arrangement of the autoclave is preferable for permitting charging with rubber dough.

The autoclave is illustrated with four concentric steel cylindrical shells I 0, I I, I2 and I3.

These shells form corresponding annular chambers I4, I5 and I0. The central or gassing chamber I1 of the autoclave is made of sufcient diameter and volume to encase the maximum charge of rubber dough. The central cylindrical shell I3 is preferably made thicker and stronger than the other shells.

The autoclave is mounted on a base 39 which is bolted to the flange I8 extending from the base of outer shell I0 by stay-bolts I9. Circular rims 20 and 2I spaced between the bottom ends of shells I0, II and I2 maintain them properly spaced. The joints between the rims 20 and 2| and the shells are welded to insure a perfect pressure seal for the chambers I4 and I5. The central shell I3 has a flange 2| at its bottom end which is welded with the adjacent shell I2 end to form annular pressure chamber I6.

The top end of the autoclave contains the circular rims 22 and 23 corresponding to the rims 20 and 2! for sealing the corresponding end of the chambers I4 and I5. 4A flange 24 at the top end of the inner shell I3 closes the corresponding end of the chamber` I6. The annular chambers I4, I5 and I5 are sealed to retain the high pressures to be described hereinafter.

A cover 25 is tted at the top end of the autoclave and is fixed into position thereon between stay-bolts 2B set into flange 21 at the top end of the outer shell IB. An eye-bolt 30 is attached centrally to the cover 25 to permit removal from position by a crane or other power operated device. An annular projection 28 at the top end of the inner shell I3 is provided to coact with a corresponding annular recess in the cover plate 25 together with a gasket 29 for rendering the inner chamber I1 gas tight at the high pressure it is subjected to.

A series of concentric piping 3i is arranged at one portion of the autoclave to communicate with the internal chambers for maintaining them at suitable pressures. A pipe 32 communicates directly to the inner chamber I1. An inert gas at the necessary high pressure is passed through pipe 32 to the inner gassing chamber I1.

A concentric tube 33 connects hydraulic pipe line 34 to the annular chamber I6; a further concentric tube 35 connects hydraulic pipe line 3G to the annular chamber I5; and the outer concentric tube 31 connects the hydraulic pipe line 38 to the annular chamber I4. Although I have illustrated a series of concentric tubes to communicate gas and hydraulic pressures to the plurality of chambers, it will be evident to those skilled in the art that other forms for communieating these pressures to the chambers are feasible and need not be grouped into a concentric arrangement.

The cross-sectional View (Figure 2) illustrates the concentric annular chambers and the communicaiion thereto of the pipe lines by the concentric tubes. The inner ends of the concentric tubes 33, 35 and 31 have flanges which are welded to the corresponding shells to render them pressure tight. All the metallic joints which make up the autoclave are preferably welded or otherwise suitably sealed to insure against leaks due to the high pressures they are subjected to.

The annular chambers I4, I5 and I6 are subjected to successively higher hydraulic pressures. Liquid is introduced to the header 40 under hydraulic pressure by a pipe line from a suitable source not shown. The pipe lines 34, 36 and 38 are connected to the hydraulic header 40 through corresponding pressure reducing valves 44, 46 and 48. Corresponding pressure gauges 43, and 41 are used on the pipe lines to indicate the suitable differential pressures which the annular chambers are subjected to.

An inert gas such as nitrogen is generally used for gassing the rubber dough. 'I'he gas is fed from a suitable compressor to the chamber I1 through pipe line 32. A pressure gauge 4I and pressure reducing valve 42 are inserted in the pipe line 32.

The heating arrangement within the autoclave is illustrated With steam coils arranged along the inner Wall of the shell I3. The steam coils are arranged in two sections, namely a central. section and the outer sections 5I-52 which are interconnected in series.

Steam is applied to the steam main 53 from which the steam pipes 54 and 55 are tapped to supply the corresponding steam coil sections 50 and 5I-52. Corresponding pressure control valves 55 and 51 are inserted in the steam lines together with pressure gauges 58 and 59. A steam trap 60 and BI is connected to the ends of the steam coil sections. The inlet and outlet pipes for the steam coil sections are sealed at the portions where they pass through the inner shell I3 to prevent any leak due to the high gaseous pressure within the chamber I1.

The central steam coil section 50 is maintained at a lower steam pressure than the end section seam coils .5I- 52. The higher steam pressures at the end sections will compensate for the higher temperature gradient normally at these zones t0 maintain a more uniform heating or temperature gradient throughout the whole gassing chamber I1. The diflerential steam pressures as indicated by gauges-58 and 59 will be determined for a particular autoclave and by the design of the relative size of the steam coil sections.

The procedure for gassing the autoclave is preferably as follows: The hydraulic pressures in the annular chambers I4, I5 and I6 are introduced simultaneously together with the inert gas in the chamber I1. Although I have illustrated three annular chambers about the central gassing chamber, it is to be understood that this is by example only and more or less annular chambers are feasible. The differential pressures between the chambers I4 to I1 are dependent upon the particular design of the autoclave.

These differential pressures may be the same between each successive chamber or may vary in accordance with the design of the successive shells. The shells may be progressively thicker or stronger from the outer shell to the inner one or vice versa. In the following example I shall for simplicity refer to equal differential chamber pressures of 2000 pounds per square inch and use a central chamber pressure of 8000 pounds per square inch.

When chamber I1 is subjected to a gaseous pressure of 8000 pounds per square inch, the pressure gauge 4I will indicate this pressure. The pressure of the rst annular chamber I6 is adjusted to 6000 pounds as indicated by gauge 41; the next chamber I 5 is adjusted to 4000 pounds as indicated by gauge 45; and the chamber I4, to a pressure of 2000 pounds as indicated by gauge 43. It will be evident that no shell is subjected to a their input pressures.

' may tend to increase the pressure in the chambers. ReliefY valves 62 to 65 are preferably attached to the input pipe lines of these chambers to avoid excessive pressure increase or pressure unbalance between the chambers.

Hydraulic pressure supplied to chambers I4, I and I6 will minimize the danger of explosion of thehigh pressure autoclave. Since the liquid is substantially'incompressible, a leak will not require tremendous volume increase as do expandible gases, but merely gradually reduce the chamber pressure during the leak. The central shell I3 is preferably made stronger than the other shells even though it is designed for a 2000 pound differential since it contains a gas and is directly subjected to the heating coils and mechanical jars due to insertion and removal of the rubber dough charging. v.Another advantage of the hydraulic pressure in the annular chambers is the relatively less expensive apparatus required to produce corresponding high pressures in the chambers than gas compression machinery.

It is to be understood that the pressure reducf ing valves 42, 44, 46 and 48 are adjusted toV automatically produce the requisite pressures in the autoclave chambers. Any tendency for one or more chambers to exceed the predetermined pressure will operate the correspondingly preset relief valves 62 to 65 to maintain the proper pressures. The pressure settings of the automatically functioning pressure reducing valves 42, 44, 46 and 48 may be changed in a manner wellV known in the art for different operating pressures for the autoclave. For a given setting, the hydraulic and gas .pressures are admitted simultaneously into the chambers to maintain the predetermined pressure differences between the plurality of shells of the autoclave.

I claim:

1. In an autoclave, a central high'pressure gas chambenna removable gas-tight cover for said chamber; a plurality of spaced shells concentric about said chamber forming corresponding annular chambers; said plurality of spacedshells containing liquid under lower pressure than the gas in the central high pressure gas chamber, means for automatically maintaining constant liquid pressures in said concentric annular chambers, said constant pressures being individually less than the pressure in said central high pressure gas chamber, said constant pressures being greatest in the innermost concentric chamber and least in the outermost concentric chamber, said means comprising individual pipe lines connected to each of said chambers, means for generating constant pressures in said annular chambers through the pipe lines including a hydraulic feeder for supplying liquid under pressure to said annular chambers, an automatic pressure reducing valve in each pipe lineV for reducing the pressure from said feeder to predetermined constant values, a relief valve in said pipe lines for maintaining said predetermined annular chamber pressures, means for maintaining a predetermined gaseous pressure in said central high pressure gas chamber; Vmeans for maintaining said central chamber substantially uniformly heated'comprising a central helical steam coil, end section helical steam coils and independent means for controlling the heating by said steam coils.

2. In a high pressure device, a central cylindrical high pressure gas chamber, a removable gas-tight cover for said chamber; a plurality of spaced shells concentric about said chamber, said shells being sealed at their ends to form corresponding air-tight chambers and being substantially coextensive with said chamber; said plurality of spaced shells containing liquid under lower pressure than the gas in the central high pressure gas chamber, means for automatically maintaining constant liquid pressures in said concentric Vannular chambers, said constant pressures being individually less than the pressure in said central high pressure gas chamber, said constant pressures being greatest in the innermost Vconcentric chamber and least in the outermost Yconcentric chamber, said means comprising individual pipe lines connected to each of said chambers through concentric connection joints, means for simultaneously generating predetermined liquid hydraulic pressures in said annular chambers through the pipe lines including 4a hydraulic feeder for supplying liquid under pressure to said annular chambers, anautomatic pressure reducing valve in each pipe line for reducing the pressure from said feeder to predetermined values, a relief valve in said pipe lines for maintaining said predetermined annular chamber pressures, means for maintaining a predetermined gaseous pressure in said central high pressure gas chamber; means for maintaining said central chamber substantially uniformly heated comprising a central helical steam coil, end section helical steam coils and independent means for controlling the heating by said steam coils. JAMES S. REID. 

